Bateson - "Body-in-the-environment"

"We commonly think of the external 'physical world' as somehow separate from an internal 'mental world'. I believe that this division is based on the contrast in coding and transmission inside and outside the body. (...)In considering units of evolution, I argued that you have at each step to include the complete pathways outside the protoplasmic aggregate, be it DNA-in-the-cell, or cell-in-the-body, or body-in-the-environment. The hierarchic structure is not new. Formerly we talked about the breeding individual or the family line or the taxon, and so on. Now each step of the hierarchy is to be thought of as a system, instead of a chunk cut off and visualized as against the surrounding matrix. (...) It is the attempt to separate intellect from emotion that is monstrous - and dangerous - to attempt to separate the external mind from the internal. Or to separate mind from body".  

Gregory Bateson - Steps to an Ecology of Mind